FN MAG SLEEVE FN 509M 9MM 17RD SLEEVE FOR 17RD MAG BLACK20-100355 20100355

FN MAG SLEEVE — FN 509M 9mm — 17-Round Magazine Sleeve, Black (20-100355 / 20100355 / UPC 845737010164) Short meta description (SEO): FN MAG SLEEVE for the FN 509M — black polymer 17-round magazine sleeve (part #20-100355 / 20100355). Convert full-size 17-round FN magazines for comfortable, reliable use in FN 509 Midsize pistols. UPC 845737010164. Product Overview The FN MAG SLEEVE (20-100355 / 20100355) is a factory-fit polymer magazine sleeve engineered to adapt FN 17-round 9mm magazines for use with the FN 509 Midsize (509M) platform. Made from impact-resistant polymer, this OEM sleeve slides over a 17-round magazine to provide a secure, ergonomic grip surface, prevent over-insertion, and deliver a near-factory fit and finish on the midsize frame. It’s a small, inexpensive accessory that makes running full-size capacity mags in a midsize pistol both practical and comfortable. MidwayUSA+1 Key Features Fit / Model: FN 509M (Midsize) — designed specifically for 17-round 9mm magazines. GunMag Warehouse+1 Manufacturer Part Numbers: 20-100355 (SKU) / 20100355. GrabAGun+1 UPC: 845737010164. GrabAGun Material: Durable, impact-resistant polymer for lightweight strength and longevity. GunMag Warehouse Color: Black — low-profile, OEM appearance. OpticsPlanet Installation: Tool-free slide-on design for fast installation and removal. MidwayUSA Why You Need This Sleeve Using a full-size 17-round magazine in the FN 509 Midsize without a sleeve can leave the magazine over-inserting, produce an awkward grip, or create an inconsistent ride height. The FN MAG SLEEVE restores the intended grip geometry, adds a comfortable palm surface, and prevents excess magazine movement — all while preserving reliable feeding and magazine seating. It’s the go-to accessory for shooters who want the capacity of a full-size mag with the handling benefits of a midsize pistol. dfcarms.com+1 Performance & Practical Benefits Improved Ergonomics: Extends the grip surface in the correct location so the pistol handles naturally with a 17-round mag installed. GunMag Warehouse Factory Fit & Finish: OEM design ensures seamless integration with FN 509M frames and minimal snag for concealment or draw. Palmetto State Armory+1 Durability: Robust polymer resists dings, scratches, and everyday carry abuse. GunMag Warehouse Cost-Effective: An inexpensive upgrade that solves common fitment and comfort issues when running larger magazines in midsize pistols. GrabAGun Compatibility & Fitment Notes Specifically intended for the FN 509 Midsize (509M) pistols using the OEM 17-round 9mm magazine. It does not convert full-size frame geometry and may not be compatible with aftermarket magazines that differ in external dimensions. Always verify magazine model and fit before purchase. The Mag Shack+1 Installation & Use Ensure the magazine is unloaded and the firearm is clear. Slide the FN MAG SLEEVE over the 17-round magazine until it seats flush with the magazine body. Insert the magazine into the 509M and confirm proper seating and retention. Function-check (dry) to ensure reliable feed and release. The sleeve is tool-free and reversible — remove it for range use or re-install for everyday carry as desired. MidwayUSA+1 Care & Maintenance Wipe clean with a damp cloth and mild soap if needed. Avoid harsh solvents for prolonged exposure. Inspect periodically for cracks or excessive wear — replace if any damage is found to maintain secure fit and reliable operation. GunMag Warehouse Who Should Buy This FN 509M owners who want to run 17-round magazines without compromising grip ergonomics. Concealed carriers seeking a low-profile solution to retain full-size capacity in a midsize package. Range users and instructors who swap between full-size and midsize configurations and need consistent handling. Any shooter wanting an OEM, reliable, and affordable mag sleeve replacement. dfcarms.com SEO Keywords (for search optimization) FN MAG SLEEVE, FN 509M mag sleeve, FN 509M 17-round sleeve, 20-100355, 20100355, UPC 845737010164, FN 509 midsize magazine sleeve, 9mm 17rd sleeve, FN magazine adapter sleeve, OEM FN mag sleeve. Final Thoughts Small accessories make a big difference. The FN MAG SLEEVE (20-100355 / 20100355) offers a factory-fit, durable, and affordable way to use 17-round magazines in your FN 509M while restoring natural ergonomics and reliable function. If you want the capacity of a full-size magazine with the handling of a midsize pistol, this sleeve is an essential, no-fuss solution. MidwayUSA+1 The End